Spam Issue Viewed As IT Security Failure

Computerworld - The problem of unwanted e-mails may not be the biggest security threat my company faces, but it's a highly visible failure to our employees and threatens to taint the IT security group's good reputation.
One of the ways that staffers judge good security is if they can work free of fear. We score pretty well on that measure. Our managers don't fear that our business systems will be compromised or corrupted, our desktop users no longer fear virus infections, and I generally don't fear large security incidents looming on the horizon. Life is good. Apart from spam, that is.
Because many of our staffers work with customers, they often publish their e-mail addresses on our Web site and in our publications. These staffers get flooded with hundreds of rubbish messages along with real customer e-mails.
They get offered radio-controlled cars, free money from Nigeria and, perhaps most bizarrely, septic tanks. That flood is bad enough, but mixed in with all the commercial rubbish are darker-themed messages -- come-ons to pornographic Web sites and hate sites, as well as abusive e-mails.
These frontline staffers constantly face high volumes of offensive content, and until recently, we had done little about it.
The problem became bad enough that it presented a risk to our productivity. Staffers were worried by the content, our e-mail systems were spending time on spam rather than on customer e-mails, and the problem affected employees at all levels.
Turning to Blacklists
The first option we looked at was using a blacklist service, which takes spam reports, identifies the servers used and publishes the addresses so that our e-mail server can automatically shun further e-mails from those sources. But spammers move to new servers faster than the blacklist can keep up. Another drawback: Once a company is on the blacklist, its e-mail administrator must jump through hoops to get it removed. Meanwhile, any legitimate e-mail from that company is blocked. Blacklists are useful and have made a dent in spam volumes, but this tool alone wasn't good enough for us.
We ended up going with a more elaborate service from MessageLabs Ltd., a Minneapolis-based service provider we were already using for e-mail traffic virus scans. The company offers a service to label spam using both blacklists and heuristics. As far as I can tell, this means MessageLabs has found a set of features associated with spam, produced a weighting for those features and established a threshold above which something is marked as probable spam.
For example, if an e-mail says,